btrfs: init root block_rsv at init root time

In the future we're going to have multiple csum and extent root trees,
so init the roots block_rsv at setup_root time based on their root key
objectid.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/block-rsv.c

@@ -412,6 +412,29 @@ void btrfs_update_global_block_rsv(struct btrfs_fs_info *fs_info)
 	spin_unlock(&sinfo->lock);
 }
 
+void btrfs_init_root_block_rsv(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+
+	switch (root->root_key.objectid) {
+	case BTRFS_CSUM_TREE_OBJECTID:
+	case BTRFS_EXTENT_TREE_OBJECTID:
+		root->block_rsv = &fs_info->delayed_refs_rsv;
+		break;
+	case BTRFS_ROOT_TREE_OBJECTID:
+	case BTRFS_DEV_TREE_OBJECTID:
+	case BTRFS_QUOTA_TREE_OBJECTID:
+		root->block_rsv = &fs_info->global_block_rsv;
+		break;
+	case BTRFS_CHUNK_TREE_OBJECTID:
+		root->block_rsv = &fs_info->chunk_block_rsv;
+		break;
+	default:
+		root->block_rsv = NULL;
+		break;
+	}
+}
+
 void btrfs_init_global_block_rsv(struct btrfs_fs_info *fs_info)
 {
 	struct btrfs_space_info *space_info;
@@ -426,22 +449,6 @@ void btrfs_init_global_block_rsv(struct btrfs_fs_info *fs_info)
 	fs_info->delayed_block_rsv.space_info = space_info;
 	fs_info->delayed_refs_rsv.space_info = space_info;
 
-	/*
-	 * Our various recovery options can leave us with NULL roots, so check
-	 * here and just bail before we go dereferencing NULLs everywhere.
-	 */
-	if (!fs_info->extent_root || !fs_info->csum_root ||
-	    !fs_info->dev_root || !fs_info->chunk_root || !fs_info->tree_root)
-		return;
-
-	fs_info->extent_root->block_rsv = &fs_info->delayed_refs_rsv;
-	fs_info->csum_root->block_rsv = &fs_info->delayed_refs_rsv;
-	fs_info->dev_root->block_rsv = &fs_info->global_block_rsv;
-	fs_info->tree_root->block_rsv = &fs_info->global_block_rsv;
-	if (fs_info->quota_root)
-		fs_info->quota_root->block_rsv = &fs_info->global_block_rsv;
-	fs_info->chunk_root->block_rsv = &fs_info->chunk_block_rsv;
-
 	btrfs_update_global_block_rsv(fs_info);
 }
 

fs/btrfs/block-rsv.h

@@ -50,6 +50,7 @@ struct btrfs_block_rsv {
 };
 
 void btrfs_init_block_rsv(struct btrfs_block_rsv *rsv, unsigned short type);
+void btrfs_init_root_block_rsv(struct btrfs_root *root);
 struct btrfs_block_rsv *btrfs_alloc_block_rsv(struct btrfs_fs_info *fs_info,
 					      unsigned short type);
 void btrfs_init_metadata_block_rsv(struct btrfs_fs_info *fs_info,

fs/btrfs/disk-io.c

@@ -1140,7 +1140,12 @@ static void __setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info,
 			 u64 objectid)
 {
 	bool dummy = test_bit(BTRFS_FS_STATE_DUMMY_FS_INFO, &fs_info->fs_state);
+
+	memset(&root->root_key, 0, sizeof(root->root_key));
+	memset(&root->root_item, 0, sizeof(root->root_item));
+	memset(&root->defrag_progress, 0, sizeof(root->defrag_progress));
 	root->fs_info = fs_info;
+	root->root_key.objectid = objectid;
 	root->node = NULL;
 	root->commit_root = NULL;
 	root->state = 0;
@@ -1151,7 +1156,8 @@ static void __setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info,
 	root->nr_ordered_extents = 0;
 	root->inode_tree = RB_ROOT;
 	INIT_RADIX_TREE(&root->delayed_nodes_tree, GFP_ATOMIC);
-	root->block_rsv = NULL;
+
+	btrfs_init_root_block_rsv(root);
 
 	INIT_LIST_HEAD(&root->dirty_list);
 	INIT_LIST_HEAD(&root->root_list);
@@ -1189,6 +1195,7 @@ static void __setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info,
 	root->log_transid = 0;
 	root->log_transid_committed = -1;
 	root->last_log_commit = 0;
+	root->anon_dev = 0;
 	if (!dummy) {
 		extent_io_tree_init(fs_info, &root->dirty_log_pages,
 				    IO_TREE_ROOT_DIRTY_LOG_PAGES, NULL);
@@ -1196,12 +1203,6 @@ static void __setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info,
 				    IO_TREE_LOG_CSUM_RANGE, NULL);
 	}
 
-	memset(&root->root_key, 0, sizeof(root->root_key));
-	memset(&root->root_item, 0, sizeof(root->root_item));
-	memset(&root->defrag_progress, 0, sizeof(root->defrag_progress));
-	root->root_key.objectid = objectid;
-	root->anon_dev = 0;
-
 	spin_lock_init(&root->root_item_lock);
 	btrfs_qgroup_init_swapped_blocks(&root->swapped_blocks);
 #ifdef CONFIG_BTRFS_DEBUG